“As of 5 p.m. Friday, DTE’s access to the plant remains limited, as teams continue to assess the situation,” the utility said. “The plant remains closed, and we do not have an estimate as to when the plant will reopen.”

Fire crews on Friday extinguished the blaze reported at 6:30 p.m. Thursday and sent smoke into the air that was visible for miles, officials said. The fire started in a coal-fired generating unit. There were no injuries in the incident.

“DTE teams successfully invoked emergency procedures and shut down all generating units at the site while working with first responders to successfully control the situation,” DTE Energy said Friday.

Firefighters from across St. Clair County ended up called to the plant about 40 miles northeast of Detroit and along the St. Clair River as thick, billowing black and gray smoke rose from the burning structure. Employees safely evacuated.

Traffic ended up detoured away from the plant.

The St. Clair Fire Department said Friday crews went into the building overnight to look for hot spots and remained at the plant, located along the U.S. border with Canada.

The utility said customers won’t see any effects on electrical service. Air quality readings were “well within normal limits outside the facility perimeter,” DTE said.

The plant has been in service since 1953 and the utility said the facility has 294 employees overall.

DTE said in June that coal-fired units at the plant are among eight at three of its facilities slated to be shut down within the next seven years.